EFI random bog down lean codes

[Timmy390]

Got an odd issue with my EFI. It's OBD1 SN95 Stang. 96 van speed density converted to 95 Stang mass air. Been running great for 2 plus years......then the oddness started this summer.

First thing I noticed was the idle.....it randomly hangs at 1500 It will not go down while driving. If I stop and unplug the TPS and reconnect it, the issue goes away.

Second, out of the blue while driving say 45 on a back country road, it's odd. Power drops off bigtime. No bucking or missing or anything....just no power. Press the gas an nothing happens. It throws codes 172 and 176 Lean condition on both banks but no other codes. Power picks back up after maybe 1 to 2 seconds and runs normal. The tac didn't drop so had spark.....thought water in the tank but the prefilter is clean.....

It's never bogged down while driving hard....and I got a heavy right foot. Only does this while driving easy.

Any ideas? I was thinking TPS but now thinking MAS. Checking fuel pressure is not going to be easy. Van fuel rail and Explorer upper have the port blocked. No access or room to hook up the gauge.

Tim

 

[Timmy390]

Drove it at lunch. Bout 8 miles where it drove fine. Sat for an hour and on the way home....it dropped out twice. Once with clutch in rolling to a stop at a red light and once while sitting at a red light.

Total drop out. RPM's fell....like it shut off half a second. No codes popped. Going to look for issues with the ignition. I realized it's only done it after being driven, stilling for an hour and then driving back home. Always after it's sat hot......

Tim

 

[fishinman78]

I would check your ignition coil. Does that have a TFI module on the distributor?

 

[DirtDonk]

And when the clutch was in, did the engine die completely or just go down to idle and sit there?

Paul

 

[Timmy390]

I would check your ignition coil. Does that have a TFI module on the distributor?

It's remote.....

I hate to throw parts at it but with OBD1 ECM feedback is somewhat limited but yes, coil is on my list


Tim

 

[Timmy390]

And when the clutch was in, did the engine die completely or just go down to idle and sit there?

Paul

It was a short event but as far as I could tell, total shutoff......While setting at the light I know for sure.....it totally cut out.

Tim

 

[Broncobowsher]

After the fuel filter, that is where to put a T-fitting to check fuel pressure.

 

[Timmy390]

After the fuel filter, that is where to put a T-fitting to check fuel pressure.

I may have to do that. Great idea......

Tim

 

[Timmy390]

Sorry for such a lag in updating this. Deer season and working on my Samurai. Time flies

I swapped out all the determined to be counterfeit Motorcraft plugs I got off RockAuto as well as added new coil connector and TPS connector. Both were a bit ragged.

Drove the rig 3 times since the changes. No more bog and no codes. Seems to be running better than ever. Fingers crossed it's solved.

Tim